Silencing of hypoxia-inducible factor-1α gene attenuates chronic ischemic renal injury in two-kidney, one-clip rats

Abstract

Silencing of hypoxia-inducible factor-1␣ gene attenuates chronic ischemic renal injury in two-kidney, one-clip rats. Am J Physiol Renal Physiol 306: F1236 -F1242, 2014. First published March 12, 2014 doi:10.1152/ajprenal.00673.2013.-Overactivation of hypoxia-inducible factor (HIF)-1␣ is implicated as a pathogenic factor in chronic kidney diseases (CKD). However, controversy exists regarding the roles of HIF-1␣ in CKD. Additionally, although hypoxia and HIF-1␣ activation are observed in various CKD and HIF-1␣ has been shown to stimulate fibrogenic factors, there is no direct evidence whether HIF-1␣ is an injurious or protective factor in chronic renal hypoxic injury. The present study determined whether knocking down the HIF-1␣ gene can attenuate or exaggerate kidney damage using a chronic renal ischemic model. Chronic renal ischemia was induced by unilaterally clamping the left renal artery for 3 wk in Sprague-Dawley rats. HIF-1␣ short hairpin (sh) RNA or control vectors were transfected into the left kidneys. Experimental groups were shamϩcontrol vector, clipϩcontrol vector, and clipϩHIF-1␣ shRNA. Enalapril was used to normalize blood pressure 1 wk after clamping the renal artery. HIF-1␣ protein levels were remarkably increased in clipped kidneys, and this increase was blocked by shRNA. Morphological examination showed that HIF-1␣ shRNA significantly attenuated injury in clipped kidneys: glomerular injury indices were 0.71 Ϯ 0.04, 2.50 Ϯ 0.12, and 1.34 Ϯ 0.11, and the percentage of globally damaged glomeruli was 0.02, 34.3 Ϯ 5.0, and 6.3 Ϯ 1.6 in sham, clip, and clipϩshRNA groups, respectively. The protein levels of collagen and ␣-smooth muscle actin also dramatically increased in clipped kidneys, but this effect was blocked by HIF-1␣ shRNA. In conclusion, long-term overactivation of HIF-1␣ is a pathogenic factor in chronic renal injury associated with ischemia/hypoxia. collagen; ␣-smooth muscle actin; renal fibrosis; chronic kidney diseases REDUCED RENAL TISSUE OXYGEN levels have been demonstrated in a large variety of chronic kidney diseases (CKD) in both human patients and in experimental animal models. Hypoxia in CKD results from a combination of structural and functional changes (12, 36). As a result, hypoxia-inducible factor (HIF)-1␣ has been reported to be consistently upregulated in almost all types of CKD (7, 16, 17, 36 -38). However, it is unclear whether upregulation of HIF-1␣ is beneficial or deleterious in progressive CKD. HIF-1␣ is a transcription factor and has been shown to stimulate collagen accumulation (7,15,43,44) and promote the epithelial-to-mesenchymal transition (EMT) (11,35), an important mechanism involved in the progression of CKD (3,33,57,67). Therefore, although upregulation of HIF-1␣ is protective in acute kidney injury (9, 18, 37, 53), ample evidence indicates that long-term overactivation of HIF-1␣ may be a pathogenic factor in CKD (10,16,21,24,36,45).Previous studies have shown that genetic ablation of renal epithelial HIF-1␣ inhibits the development of renal tubulointerstitia...

Myeloid HIF-1 attenuates the progression of renal fibrosis in murine obstructive nephropathy

“…These reports suggest that global activation of HIFs is protective in the development of renal fibrosis. In contrast, it was reported that silencing of HIF-1 by small hairpin RNA attenuated renal fibrosis in angiotensin Ⅱ induced renal injury (39) and in two kidney, one clip chronic ischemic renal injury model (40). These reports suggest the detrimental effect of HIF-1 in the progression of renal fibrosis.…”

Expression and contribution of the HIF‑1α/VEGF signaling pathway to luteal development and function in pregnant rats

“…HIF-1, a helix-loop-helix transcriptional factor, which consists of HIF-1α and HIF-1β, has been cloned and characterized as a transcriptional activator of several oxygen-sensitive genes, including erythropoietin, heme oxygenases, transferrin and several glycolytic enzymes (27)(28)(29)40), whose protein products are important in developmental and physiological processes, including angiogenesis, erythropoiesis, glycolysis, iron transport and cell proliferation/survival (2,5,11,(41)(42)(43). It has been reported that HIF-1α protein is inducible by a decrease of O 2 concentration in tissue or cells.…”

“…The PCR conditions of the RT-qPCR system (Applied Biosystems Life Technologies), were as follows: 50˚C for 2 min, 95˚C for 10 min, followed by 40 cycles at 95˚C for 15 s, and 60˚C for 1 min. The relative gene expression levels were calculated in accordance with the ΔΔCt method (26)(27)(28)(29). Relative mRNA levels were expressed as 2…”

Salidroside Attenuates Adriamycin-Induced Focal Segmental Glomerulosclerosis by Inhibiting the Hypoxia-Inducible Factor-1α Expression Through Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway

“…HIF-1α plays a crucial role in pathogenesis of chronic kidney disease (CKD). Silencing of hypoxia-inducible factor-1α gene could attenuate chronic ischemic renal injury [13]. Besides, neotuberostemonine inhibits the differentiation of lung fibroblasts into myofibroblasts in mice by regulating HIF-1α signaling [14].…”